stuck

Affinity is a 64bit application so it won't be in the C:\Program Files (x86) folder, look here instead: C:\Program Files\Affinity\Photo As to where downloads end up, that depends on how your browser is configured but the first place to look is the Downloads folder, which is here: C:\Users\[yourProfileNameHere]\Downloads

I can't reproduce this effect. Can you give more details of your workflow within DxO? For example: 1) Which DxO product and version are you using, Photolab 5 (Essential / Elite)? 2) What type of file did you process in DxO? RAW (format) / TIFF (16bit/8bit/8bit compressed) / JPEG (quality)? 3) What edits did you apply to the file? (If you can upload the .dop file that will show the edits you used) 3) In which format did you export your edited file? TIFF (16bit/8bit/8bit compressed) / JPEG (quality)?

1) Do you actually mean "use the DxO Nik Collection of plugins within Affinity Photo", If so which Nik plugin is giving this colour shift? Or do they all do it? 2) When you say you've passed the problem on to DxO, do you mean you've submitted the problem direct to DxO Support via this page: https://support.dxo.com/hc/en-us/requests/new If you have not also posted about this problem on the DxO User Forum: https://feedback.dxo.com/ you should do so. You will get a faster response from the DxO users there than from DxO Support. 3) When you say, "optimised for Lightwave", do you mean the Nik plugins seem to work better in Adobe Lightroom?