second hand laptop

I purchased this laptop two days ago abs the seller was quite dodgy with the interaction. I have deleted windows and restarted. When on the account page on fresh start the domain is set to a company which isn’t allowing me to create an account - I have to use offline account to use the laptop...

My budget is £300. £350 max if the extra cost is worth it. I'm going to use the laptop for university and music production. I've built my own PC before so I can happily upgrade the laptop if necessary. If you didn't see it in the title, I am looking for a laptop in the second hand market as...