You've received or downloaded a modpack that is meant for Curse Client but for whatever the reason is not found on the Curse Client mod pack browser.
Instructions:
1. with Curse client open, goto the Minecraft pack screen
2. click on the bottom button which says "create custom profile"
3. a new screen pops up
4. The title of the screen is "Create Profile"
5. Do not fill out anything!
6. There is sentence below the title, it says "Or import a custom profile ..."
7. click the word "import" which is probably in a green color.
8. a dialogue pops up asking you for the profile, select the profile and choose open
9. the pack begins installing
10. now play it.
Cheers, And I hope this explains how to install a custom modpack in Minecraft Curse Client.
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