I have a new laptop and I want to download the software but the Add computer link is disabled
Sorry about that, Yasser. We're working on getting some of the account functions repaired. In the meantime, you can use this link to download the desktop software for your new laptop. I hope all goes well in getting things set up again!
The link doesn't seem to work for (Linux) Mint.
For Linux, the best approach is to install the "boinc" package via the package manager on your system; I think that would be apt on Mint. There's a bit more detail in the wiki article: Welcome Linux Users