When installing the ThinLinc server on Linux, there are many different distributions to choose from. Cendio does not recommend any particular distributions or versions of Linux. Which one you choose will depend on your own particular use-case and individual preferences.
ThinLinc does have a minimum set of server-side requirements, which can be found in the ThinLinc Administrator’s Guide (TAG) here. Most modern distributions should easily meet these requirements, including popular ones such as Ubuntu, Red Hat Enterprise Linux (RHEL), SuSE and CentOS. All of these should work equally well with ThinLinc.