I cannot update the access points CAP from CAPs MAN v2. The CAPsMAN v2 is a CCR2004-1G-12S+2XS, the access points (CAPs) are cAPGi-5HaxD2HaxD.
It seems that the CAPs are missing the firmware file wifi-qcom-7.18.2-arm64.npk. I have searched the Mikrotik documentation but have not found a solution.
Question: How do I configure the remote firmware update for the CAPs from the CAPsMAN v2 router?
Upload all the relevant packages (base routeros and necessary optional packages, such as wifi-qcom) for all relevant architectures (ARM, ARM64) to capsman device … I recomend you to create a dedicated folder on flash storage). Then set package-path to the correct folder and set upgrade-policy to something different than “none”, I’d go with suggest-same-version. Both properties are under /interface/wifi/capsman.
seppuku may be less painful 
Does this mean that there is no automated solution to download the required files (wifi-qcom-7.18.2-arm64.npk) to the CAPsMAN v2 device?
Do I have to do it manually? And also before updating the CAPsMAN v2 device?
No, there’s no automated way of downloading additional packages to capsman device.
I heard that capsman can use own installed packages to upgrade cap devices (which probably explains what you described in OP), but that’s not enough if capsman device doesn’t have certain packages installed (or if capsman is not even same architecture as caps). What you can try is to install wifi-qcom package (since 7.18 that’s possible to do via UI, no manual file download necessary) … that package is not needed for CCR, it’ll consume some flash storage and some RAM (for the later, you can try to disable package but keep it installed). And see if cap devices get upgraded.
Thus method can fail in case there are caps requiring contradicting packages (e.g. wifi-qcom v.s. wifi-qcom-ac), I guess in such case some experimentation would provide an answer.
My experience with legacy cspsman was that “package storage” could contain a mix of architectures and optional packages and versions … and cap would fetch only those necessary. So it just takes storage.
If you go this path … then you don’t have to provide new packages vefore you upgrade capsman if upgrade-policy is not set to “require…”.
Thanks @mkx, somehow Mikrotik didn’t pay attention or made a design mistake, it’s not convenient.
Meanwhile, I tried to download the all_packages-arm64-7.18.2.zip to the switch with a script, but I can’t extract the wifi-qcom-7.18.2-arm64.npk from the .ZIP. The router OS does not seem to have a way to extract a .ZIP file. This is a loss for Mikrotik.