Cyber space in Sonic Frontiers is very different from the overworld in many ways, including the in-game timer, spindashes, etc.
This page and its subpages contain info on how to approach cyber space in general, as well as each individual level (IL).
Action marks are the colored triangles on the icon displayed next to your time in arcade mode and cyber space challenge. They represent certain actions or settings used in the cyber space run, as following:
Grey: Shown if you use a magdash at any point during your run.
Red: Shown if you spindash at any point during your run.
Yellow: Shown if either "Set the deceleration rate" or "Jump deceleration" are set to a value below 100.
Blue: Shown if the "Cyber space power boost" setting is enabled
Purple: Shown if the "Maintain boost during a jump" setting is enabled.
There are 4 different categories for each cyber space level. Unrestricted and Restricted are in the main boards, while All missions and No action marks are in category extensions. The rules are the following:
Unrestricted: Clear the level, with no restrictions.
Restricted: Clear the level while only using the grey and purple action marks.
All missions: Clear the level while clearing all of the missions displayed at the end of the level in the main game, such as collecting all red rings, collecting a certain amount of rings, and clearing the level with S rank time.
No action marks: Clear the level without using any of the 5 action marks.
Cyber space is primarily used in fullgame runs to give you vault keys.
Each cyber space level gives a key for each mission completed, up to 4, as well as 3 additional keys for completing every mission.
This adds up to a total of 7 keys per level.
Additionally, you don't have access to spindash in most fullgame categories, so the strats you'll need to use are different from any of the 4 cyber space IL categories.
Refer to the pages of the category you're trying to run for info on which levels you need to play.