I'm running pgadmin 4 v2.1 on win10 64 bits, and it's installed under the Postgresql 10 folder in Program Files (which for me up to now indicated it was a 64-bit version, but I see now that it seems pgadmin only exist as a 32 bit app).
With regard to upgrading to 4.30, I can only find a 32 bits installation file and that wants to install under Program Files (x86). The documentation does not say anything about these issues.
Is this a deliberate change - should I uninstall the previous version under Program Files and then install 4 v3.0 under Program Files (x86)?
Your current installation is part of the EDB PostgreSQL Installer distribution, whilst you are now trying to download the standalone community pgAdmin package. The former is available in 32 or 64 bit versions, as that is important for the database server, however the standalone pgAdmin distribution is only available as a 32bit application (there's no real benefit from running that in 64bit mode).
You can install the standalone package alongside what you have now, and either leave the existing version in place, or run the installer from Add/Remove programs and uninstall the pgAdmin component of PostgreSQL, or, there should be updated PostgreSQL installers available with pgAdmin 4 v3.0 in a few days which you can use to upgrade your PostgreSQL installation.
