Some have reported an error with Loaders Modernized v0.6.4 because they are trying to run in on Factorio < 2.0.14. This was me forgetting to adjust the dependency for 0.6.4.

Please upgrade Factorio to 2.0.14 (or later) and Loaders Modernized 0.6.7 (or later).

Thanks,
Kryojenik

Unfortunately the check box doesn't work

it says: Unknow key "strings.mdrn-use-split-lanes"

https://www.evernote.com/shard/s456/sh/e79cdeb6-38ce-c24a-f864-72e94651824d/oywVlbrSdrJNJ_64uzKWZmg0HEo7oDVBXMcXhpCWPRM4nvg8n-i8xdjR_w

I assume you're playing the game in German. I don't have a German Translations. If you'd like to provide German Translations I'd be happy to add them to the mod.

I haven't figured out crownin yet, so if you want to translate this file... everything after the '=' on each line I'd love to add them.
https://github.com/kryojenik/loaders-modernized/blob/main/locale/en/loader_modernized.cfg

yes, I play in German

The translation is not the problem now, but rather:

what should the checkbox do?
The fact is, nothing happens when you activate it!!

Can you just update and republish? Because I don't want to run experimental branch for just your mod and now my friends can't join.

Nope, the functionality that allows spit lanes was added in the 2.0.14 release of Factorio. It is not possible to have split lanes before 2.0.14.

Can you just update and republish? Because I don't want to run experimental branch for just your mod and now my friends can't join.

2.0.14 is now stable. You (and your friends) should be able to upgrade now.