Affinity V2 apps have no accessible .exe, like the V1 apps did. (They are not installed as desktop apps and calling the .exe files from a different app is blocked by file access permission issues) Serif is aware of the issue, this breaks many workflows with 3rd party apps.
That is why @shadeline2000 mentions "aflauncher.exe" which is a temporary workaround from the Affinity-Forums.
What I found to work to get Photo and Designer V2 working with CA5 is to make an .exe out of the .bat - files Affinity is also providing. (CA5 needs an .exe file...) There are ways to create an .exe out of a .bat (Google it...)
These are the BATs:
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start /b affinitydesigner2.exe %1
exit
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start /b affinityphoto2.exe %1
exit
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Also, to make it work, just like in V1, the setting in Photo and Designer "save over psd" has to be ticked.
CA5 | Affinity Photo 2 (PSD) | Affinity Designer 2 (SVG) | Davinci Resolve Studio (Video / Audio)
(Photopea to convert EPS to SVG with correct folder hierarchy)