How do I transmit my translations from Loco to www.remarpro.com?

Well, in the meantime I learned, that I can take the whole .po file and upload it.
I just wish, Loco would offer an option to download that file directly, so that one doesn’t need to use FTP and search for it (or did I overlook this option?).
Anyway, when I upload that file, it is matched to the existing translations and new or changed translations are marked as suggestions.

I just wish, Loco would offer an option to download that file directly

My plugin is not associated with WordPress and so will not interact with any WordPress properties on purpose. Firstly, because they could change their methods or terms at any time; and secondly on principle. WordPress make decisions that favour their own platform/properties that make life more difficult for third party translation tools and third party translators. This makes me disinclined to help them in return.

Well, I don’t want you to help WordPress, but to give a little help to give something back to the community. WordPress to me is the community of users, in which I include you. Since I don’t have the money to support you or other authors monitarily, I try to give back through translating.

Since Loco accesses the .po file, what it does is directly associated with the installation and from my point of view it would be easy to offer a simple download link for that .po file.

I don’t think there will be any changes made on WordPress with the purpose of hurting you or your business, but changes where we can follow and understand the reasoning. If those changes are for the good of the whole, why whould one feel offended?

it would be easy to offer a simple download link for that .po file.

WordPress already provides a way to install directly from the community translations. All you have to do is run your WordPress updater to get the latest files.

I don’t think there will be any changes made on WordPress with the purpose of hurting you or your business

There already have been. Possibly not on purpose, but they ignore criticism and suggestions that don’t favour their interest. This amounts to the same thing.