Moving files created under User1 to a second user (User2)

An authorized Apple service provider migrated the data from my 2010 iMac running High Sierra to a new MacMini (M4Pro) using a Time Machine backup. All the data had been created under the original user (User1) on the iMac, and now I want to move/copy the data under User1 on the Mini to a new user (User2). I have tried copying files from User1 to User2 but have been running into having to change permissions on every file before I can open them. I've also tried copying the files to an external SSD formatted APFS and then to User2 but am still running into the same permissions problem. Does it matter which user I am logged in as when I am moving the files around? I am currently spinning my wheels without much progress and I think I am going about this the wrong way. Any expert suggestions are welcome. Thanks!