then go grab the newest version of Ultraarc from conversion tutorial section
UltraArc Mods is what ive used lately.

Settings for new ultraarc.ini

[Options]
VolumePrefixName=Assetto_

[Split]
FirstVolumeSize=4455
CustomVolumeSize=4480
ThresholdPercent=20

pakrat2k2
can u please modify the ultraarc.ini
cause i still have on other error in the conversion

go & remove conversion folder. In first post I updated to latest Ultraarc version I use(2410). Just select gamefolder & location click start, with 18,000 files or more it can take up to 15 mins to start, be patient.

Assetto Corsa Porshe DLC with game
install size 33,4 GB
srep+exe+exe2+delta+lmza
Assetto_1 - 4.37 GB
Assetto_2 - 3.68 GB