When trying to install on rails, it says the error "Trainbuilder must be installed on rails"
https://yadi.sk/i/24N1oDCga-2qbg
You cannot put it on the ground, but shows the rails as an obstacle.

I use mods (a lot), can there be any reasons for them?

How to install it correctly?
Tried different rails, 0 difference.

When taken in hand for installation, it rotates horizontally or vertically, and if vertically, then nothing happens when you press R, and if it rotates horizontally, it rotates left / right.

Try putting it a bit more to the left, such that there is a bit of rail sticking out on the right side? It should work with vanilla rails as in your gif.

I have the same problem, including the issue with rotation. I've tried with a long rail in both directions and slid the builder all over the place. I've tried it with and without depots placed in advance. I even went and watched Xterminators video on the mod and still can't place.

Edit: Okay I figured out my issue, which is a mod conflict with Bio Industries. Bio Industries looks like it extends / overrides the vanilla rails and unfortunately this can't be disabled in the config. It would be great to have some compatibility between the two mods.

I've updated the title of this topic and I'll look into the issues Bio Industries is causing...

Hello,
have the same issue with Bio Industries installed..
it makes no difference if i use the standard or electrified rails.

thanks for fixing

Been looking at this and Bio Industries mod files. I'm not familiar enough to fully fix or %100 recognize the issue.
Could this issue be caused by the fact that BI messes with, what layers rails are interacting with?
Or that BI compounds entities? For rails are under this 'compound' rule in its code.

This is fixed in the new release.