I'm facing a challenge how to configure "cAP ac" to operate via CAPsMAN following any of available tutorials I could find.
I don't want that cAP ac operates as a router (preferred to operate as AP of the main router, since the main router has capability to manage CAP interface. Unfortunately after zillion of tries, I am almost lost what would be the right way to make it operational.
Can I kindly ask for any tutorial (step by step) how to make it operational?

For one it very much depends on ROS version running on both devices. In addition it depends on which of optional packages are installed on cAP ac. After you provide this information, we can go further.

One tutorial to follow:
https://help.mikrotik.com/docs/display/ ... iFiCAPsMAN

For one it very much depends on ROS version running on both devices. In addition it depends on which of optional packages are installed on cAP ac. After you provide this information, we can go further.

ROS for RB4011iGS+rM 7.14.2
ROS for RBcAPGi: 6.49.13

One prerequisite is to have wireless package installed on RB4011 (not wifi-qcom-ac ... which drops support for 2.4GHz radio on RB4011 anyway). Then you have to configure things in /capsman configuration subtree. When everything is configured there correctly, you should be able to put your cAP ac into CAP mode by properly pressing reset button (read cAP manual). Alternatively you can reconfigure cAP ac into CAP mode via any of UI.

Another option (possibly better) is to install ROS 7.13.2 (it seems to be the best in v7 series so far) on cAP ac ... and replace wireless package with wifi-qcom-ac. In this case you'll have to configure CAPsMAN on RB4011 under /interface/wifi (all configuration subtree, new capsman uses same profles as new wifi driver). And proceed in the same manner on cAP ac (the reset button magic or manually via UI). This solution will unleash quite some throughput (and stability) on your cAP ac, but it is a realistic possibility of running out of flash storage space ... many reports say that running this ROS/driver combination is fine if device is only used as AP (or CAP), but it's your decision.

If you encounter any problems, come back and we'll try to help sort it out.