try to attach to a database file but can't browse folder which contains the file

The Service of your SQL Server Instance hasn't enough rights to read the Data-Directory and/or the path of the folder. (Including the root of the drive to list the tree in the dialog box.) The Service needs at least the rights for listing the content of the whole path.

If this is just a testing/developing environment the best way to solve this is to configure the SQL Server Instance Service for running with the SYSTEM-Accont. The SYSTEM-Account has Access to the Root of the Drive and the Data-Folder. This eliminates also a lot of other problems.

If you are using Windows Authentication you also need to run the Management Studio as an Administrator, if you don't have enough rights on this folder.

Warning: NEVER use the SYSTEM-Account for a productive Server. Use the Exec-Command to attach Databases and ensure there are enough rights for the service to access the Data-Folder.

The user should have full access to the files, but in my opinion, attach the database while using 'sa' or another SQL Administrator, and then your database users will be able to access the databases.