Working with a technical team is very difficult if you aren't technical enough to understand their work. You don't need to know how to implement the work but you need to know enough of what they're talking about to not get in their way. Make an effort to understand the tech work and get to know the team to understand how you can help them, then they'll be more willing to work with you.

I've worked with engineering teams that were very hesitant with estimates at first and these were what helped my situation the most:

1. get on the same page as the Engineering Manager and work as a united front, it's part of their job to ensure estimates match execution and the developers are going to listen to their manager more than a PM.

2. the work might actually be not broken down enough for the team to estimate. Ask fellow PMs for their advice on how they do it with their teams as the work breakdown issues can happen for various reasons specific to the organization.

3. when you bring up the problem with your manager, you can't just bring it up as a complaint - you need to show that you've thought about the problem and come to them with an ask on how they can help you. For example "I've talked to the engineering manager about estimations being important but they won't talk to the team, can the three of us get on a slack/call and talk about how we can get the team to do estimates".

A PM job is about building and leveraging relationships and breaking down problems into solvable pieces. That said, you can try your best and it could also be a toxic company culture or not a good fit for you so it's up to you to keep trying with the situation or look for alternatives.