Roaming Profiles

I did a course for creating roaming profile and I did what the course said, that is creating hidden shared folder and changing the profile field in the user properties to \\servername\profiles$\%username% and it worked properly, but the issue that I got is when trying to make that profile mandatory, as admin on the server I cannot have access to the users folder to change the .dat extension and if I take ownership then the user who i made his profile roaming cant have access to his folder? Is there any solution for this issue? Thanks.

From my knowledge making a profile mandatory it is for sharing with multiple users. Hence taking ownership and then granting read to a group and that including multiple users within this group should provide what you need. I also remember there was an issue where a special hotfix that had to be applied since the administrator was granted access to the folder by default.

Can you let me know whether the directory containing the roaming profiles need to be on a DC?

You can try to use robocopy from the resource kit like below:

robocopy <source>\ <destination>\ /e /sec /r:1 /w:1

After that you can share the destination parent folder and unshare the old source one. In ADUC you can choose all your users at once and right click and then go to properties and then change their profile paths to \\server\profileshare\%username%.