Find Groups on Sharepoint Online Sites

Hello everyone, hope you are all well!

First of all, I apologize if the text seems strange. I don't know the language and I use an Online Translator. Even so, I intend to be quick.

A user has created a site, on this site, in a Library he has two or three folders in a hierarchy. Something like "Documents/Folder 01/Folder 02/Folder 03"

The objective is to give access permissions, manipulation to Folder 03.

To do this, access "Site Permissions / Advanced Permission Settings" and create a group, insert an external account and assign the desired level of permission to the group.

This group is usually there together with the other groups (Visitors, Members and Owners). I remove the Group from there, as I don't want its members to access the site, having seen the hierarchy issue.

I navigate to "Folder 02", and manage access to "Folder 03". There I insert the group saying what I want it to do (if it only displays or if it can be edited). Ready.

The account outside the organization, the Tenant receives the invitation email and normally accesses the Library in question. With the proper permissions without any kind of problem.

It turns out that now if I want to locate the Group to add someone else or remove it, changing the permission level is very confusing. Complicated. At least for me.

I usually only have relative success if when accessing the Site's settings, I receive this message below:
"Some of the content on this site has different permissions than what you see here. Show these items. // There are users with limited access to this site. Users may have limited access if an item or document on the site has been shared with them. Show Users."

Clicking on "Show Users." there it shows the Group and the "magic happens"

I've tried it several ways. I have read and re-read all the Documentation in this regard. And unless I misunderstood, I can't find a "smooth" way to do this. And this makes it a little more difficult to guide an organization user with less power of understanding.

For that reason, and already apologizing again, I wanted to know if you understand that it's really complicated OR if I'm the one having difficulties doing it.

Thank you very much for your help. Hugs