I have a couple of 3.6 licenses & several render node licenses that I use with Max 2018. I’m wondering if I can install the Next trial & use with Max 2018 or do I have to use the Next trial with a different install of Max, say 2019 or 2020. Thanks in advance for any info you can provide.
You can install only V-Ray 3.x or V-Ray Next in only one 3ds Max version. But you can install different versions of V-Ray in a different versions of 3ds Max. For example install V-Ray Next in 3ds Max 2018 and install V-Ray 3.x in 3ds Max 2019. You can always roll-back to the previous version if you want. Let me know if you need further information or any assistance.
is this the same for vray 5 beta? (have to uninstall next to use the beta?)
Yes, the V-Ray 5 installer will uninstall previous V-Ray versions for the same 3dsMax version