Use
MultiMC
Download the zip of the pack from the curse website.
For example;
On this page here. The download button is in the top right, a bit below the search text input field. (note: not the server files)
This zip file contains the configs and a list of needed mods called a manifesto, but not the mods themselves. Do *not* unzip it.
Then in MultiMC, click the "add instance" button. Then choose "import from zip." Then click the "browse" button. Then find the zip you just downloaded from your downloads folder. And then click "OK."
You can delete the zip file after MultiMC created the instance.
Get familiar with minecraft.curseforge.com to find the older or newer versions of the modpacks.