Search for these packs and install them similarly.

Years ago, a modder named Yufa released a series of packs that would become foundational for the community. These include: Straßenmarkierungen V3 (Road Markings):

As a last resort, you can create empty text files named after the missing splines. This stops errors but creates invisible roads – buses will fly in mid-air. Better to find the real file.

existing files to ensure all required textures are linked correctly. CreativeStreets Addon Manual for OMSI 2 | PDF - Scribd

Once you get correctly, keep it working:

Can be downloaded directly from the OMSI WebDisk .