I cloned the repo from GitHub, uploaded it to my server to an
analytics folder at my site’s root, then attempted the install via https://mysite.com/analytics/.
This gave me a few errors related to Composer and meant I had to run:
curl -sS https://getcomposer.org/installer | php php composer.phar install
as suggested by the Matomo.
I also had to install the php_curl module:
sudo apt-get install php-curl
After which I could install as per usual, so yeah, apart from working out how to install
php_curl everything works for me
Hope that helps.