Can't get plugins with custom fields in Panel to work on online server

I’m working on my first site using Kirby 3 after doing some site in Kirby 2, but I have to say I run into a lot of problems. It’s also seems quite hard to find solutions, since a lot of things point to Kirby 2 and the docs are quite confusing to me.

Anyway, a new problem I’ve run into is this: I have a working version of a website with panel running locally. The moment I’m putting this on an online server plugins with custom panel fields won’t work anymore. I have two (Kirby Builder, and Markdown). Both give the same error:
The field type "field_name" does not exist.
I installed both of the plugins by copying them into the plugin folder, and locally they just work. No problems. I tried reinstalling them on the online server the same way, but the error remains.

I did see some mentions about npm install and build in the plugins folder, but I have no idea how to get that working. I don’t have npm installed on the online server and I’m not really looking to install it just to run it in all plugins I use every time I update the site.

Any way to solve this?

Ok, so clearing the Media folder seems to have worked. No idea why, is that supposed to happen? You are probably not supposed to also upload the insides of the Media folder…?

Yes, the media folder is only temporary storage, like the thumbs folder in Kirby 2 and not supposed to be deployed.