You can find the Owner's/Users Manual here, in English:
This Document contains the Owners Manual (User Manual) AND the Quick Start Page, Specs and Photos. 53 Pages. This file hosted here only has the Owners Manual (User Manual): 01_EN_USG_9810002963_1.0_ROCKRIDER-E-ST100_16_NOV_2020
www.scribd.com
It's worth noting that Decathlon does not make the English Users Manual available. There must be a good reason, but it's frustrating.
After searching for weeks, and contacting Decathlon, only to get no help or the wrong manuals, I translated the Users Manual into English, cross-checking against the manuals in German, French and Italian (my wife is French, I speak German, and we live in Italy).
The above linked file also includes the Quick Start Page -- its only a single page, but is pretty handy.
The file also contains the full specifications for the bike, as well as photos.
Sribd.com is a pretty good host for things like this. The file is available for download; they may ask you to upload a useful document in order to be able to download this manual.
PCM