As of September 3, 2019, new Parsec users will no longer have the option to rent cloud computers. If you already have credits in your account on that date, you will have the option to keep adding credits and renting machines until January 1, 2020. After January 1, you will no longer be able to add credits to your account, and you will need to use your credits entirely by February 1, 2020. If you'd like a refund for your remaining credits, please click here.
On Steam, you want to make sure you're downloading games from a server close to your cloud PC. Sometimes, Steam doesn't pick up the correct location for that cloud PC due to how IP addresses at cloud data centers work.
Once you login to Steam, go to your account preferences, and change the download server here: