What are ways to held these guys accountable & make them take ownership?
Those are two different issues that are connected. You are the person that can hold them accountable. They cannot hold themselves accountable. That is not how this works. So it is up to you, to take action when they fail a task. For example you expected feedback, they did not deliver. Did you take any action?
Now, while it's up to you to hold them accountable, it is completely meaningless to hold someone accountable to something dictated to them. This is where "ownership" comes in.
To feel they own something, to feel they are responsible for something, they need agency. Meaning they need to be able to decide their own fate. Nothing you wrote indicates that they have that.
They usually take double the time I anticipate and still don't deliver. They just want to work in background and want to shield themselves.
I have spoken to team at least 10-15 times & gave them piece of my mind. Never heard anything back from them.
I have set clear goals. They know what is expected from them.
You tell them. You set goals. You anticipate. Did you ever ask them? If you tell me something needs to be done by Friday, I don't own that. I don't feel responsible. I have no agency, no choice here. You can yell at me if it's not done by Friday, but if you do that I only learned that you can yell. I had no choice, no actions left to change that. You can hold me accountable, but it's arbitrary and fake.
If you want me to own a task, to be responsible for it, to be accountable for it in a good way, you need to offer me agency. Ask me when I will be done and hold me to that deadline. Let me make choices and hold me to those results.
We all learned in school to be accountable. We made choices (do homework or cheat), were held accountable (passed or failed tests) and whether we liked it or not, our choices did influence the outcome. We had agency. That's why accountability worked to a degree.
Something happened to the members of your team between back then and now that made them shed their accountability. Most likely it was taken from them because they learned that being accountable but being stripped of agency is pointless.
I don't know if what happened actually happened on your team. Maybe you were unlucky enough to hire only people with bad prior experiences. More likely they experienced something in your team that made them not care. You said it yourself, they are defensive, want to "shield" themselves. It's hard to get back on track after a team is damaged that way. People don't trust easily once they have been burned. Change the lead maybe. Could it be that that was the reason you started there?
If you can demonstrate that they can own something, then you maybe have a chance. Do you have agency? Do you get asked by your boss how long something takes? If you just get told the deadlines and you cannot really make decisions, then you stand no chance. Your team knows that it's fundamentally broken. They cannot possibly take ownership of "the boss said it needs to be done in 2 weeks".
Now if you have agency. If you can influence decisions, make sure your team knows. Make sure your team is part of that. If you get asked by your boss how long it takes, don't feel pressured to give a number. Tell them you will get back to them and ask your team. Let them see how you have agency and how you own this. Then they might over time follow your lead and take ownership too.
In the meantime, hold them accountable to what they said. If you asked them how long it will take and they cannot deliver, do something about it. As a last resort maybe even replacing all of them. But don't try to make someone own something they have no agency in. That is a fool's errand, the best you would get is a phoney on-paper ownership.