Hey @maayan.m, thanks for reaching out!
Since you're on the Professional plan, there isn't a separate "workspace" layer above your team, this is only available on the Enterprise plan. So what your admin most likely updated is your team-wide permission to Can edit.
On the Professional plan, updating someone's team permission doesn't automatically unlock every folder for them. Each top-level folder is either set to "Anyone on the team can access" (inherits the team permission) or "Limited" to specific people and if it's Limited, team-wide edit permission doesn't override that.
That's almost certainly what's going on with the files you haven't accessed before. They likely live in a folder set to Limited rather than inherited, so you're not picking up Can edit there automatically.
Click Share on that folder and see whether it's set to inherit from the team, or limited to specific people. If it's limited, adding you there (or to the specific files) should take care of it.
Is this happening with files in one particular folder, or across every folder on your team?
More on how this works here: File and folder permissions.
Let me know what you find!