I can't comment on the 403 error, but I can tell you that yes you can have multiple pythons installed along side each other. Not uncommon to see python2.7 and python3.x
In Ubuntu 20.x python2.7 has been dropped...
Kstars Mac osx
Odroid C1 running indiserver (kept up-to-date with apt-get update/upgrade)
Megrez72 / HEQ5 pro / QHY5L-II-M (OAG) / Atik 314L+ / Gerd Neumann drawer