Solved, version 20.3.5 is for Kodi 20. You won’t be able to install it on current Kodi (version 19.5).

You need to wait for the devs to update it

The last version available of InputStream Adaptative (needed for the Netflix add-on) is v19.0.7 in a Pi 5 running Recalbox.
When I open Netflix, an error mensage appears telling me that for 64bit support I need at least v20.3.5, but when I try to update the pluggin in Kodi, it shows that the version installed (v19.0.7) is the last one available.

Does anyone have a newer compiled version of the InputStream to use in a Pi 5?