I just solved it by installing the R1 2021. It had the proper installation files and worked first time. Once the R1 licence server files was installed, the r2.1 worked fine. I tested it with 3 computers. All have the same story. No licence in 2.1, but there is a licence file in r1. Once you install both R1 and R2.1. Both work. So you should probably install your latest on a brand new pc without previous files hidden in system files and troubleshoot your installer.