tl;dr: This answers only the download/extract on Windows, not dependency management. Add repodata/repomd.xml to the repository's base url and then examine repomd.xml to locate and download its primary.xml file which lists the urls to download desired .rpm file(s). The script rpm2cpio.sh can extract the (compressed) cpio archive which cpio -id can then copy into the filesystem.
First, find the base url for the repository; e.g.
https://brave-browser-rpm-beta.s3.brave.com/x86_64/
Add repodata/repomd.xml to find the repository metadata; e.g.
https://brave-browser-rpm-beta.s3.brave.com/x86_64/repodata/repomd.xml
Examine repomd.xml to find the repository's primary.xml file; e.g. repodata/2635976bb02dab08a696dbaad778feea3f3351a3238fb6f77af52c651dd931cd-primary.xml.gz
Download primary.xml for the repository; e.g.
curl --output primary.xml.gz https://brave-browser-rpm-beta.s3.brave.com/x86_64/repodata/2635976bb02dab08a696dbaad778feea3f3351a3238fb6f77af52c651dd931cd-primary.xml.gz
gunzip primary.xml.gz
or use another download tool. Uncompress the file if it's compressed.
Examine primary.xml to locate the the desired .rpm archive.
grep location primary.xml
or perhaps
findstr "location" primary.xml
Download the desired .rpm file(s); e.g.
curl -O https://brave-browser-rpm-beta.s3.brave.com/x86_64/brave-browser-beta-0.67.99-1.x86_64.rpm
To unpack the contents from the .rpm file, here are some suggested utilities. Install Cygwin to run the rpm2cpio.sh script which extracts the cpio archive (probably compressed) from the .rpm file. (Use Cygwin's setup-x86_64.exe to install any script dependencies if necessary). Example:
rpm2cpio.sh brave-browser-beta-0.67.99-1.x86_64.rpm > payload
Install cpio and gunzip, xz, or bunzip using Cygwin's setup-x86_64.exe depending on how the cpio archive is packed. Figure out the format of the payload:
file payload
Now uncompress and then extract the cpio archive (An XZ compressed cpio archive in this example):
xz -d payload
cpio -id payload
Edit: alien is a much more versatile package format converter than rpm2cpio.sh. It's written in Perl. Also note that while this handles downloading and extracting RPMs on Windows (with Cygwin), it doesn't handle dependency management.