Get an error message trying to download one pack (Big Dig) other packs downloaded just fine

[violetcraft]

I just got the launcher today after having not used it for over a year, and I decided I wanted to try out Big Dig. The launcher changed since I last used it, and Big Dig wasn't one of the default packs, so I searched for it and tried to install it, but instead I got this error message "The modpack Big Dig does not appear to be installed or is corrupt, and is not available for offline play"

What does that mean? I downloaded Hexxit just fine after I tried Big Dig, so I know it's not a problem with my internet or antivirus. 

I'm sorry if this is an obvious question but I've already looked around and didn't find an answer so I figured here was the best place to ask.

[Munaus]

can you not install it at all? does the Play button not appear?

[violetcraft]

Yeah, I hit install, that error box pops up, then there is an install button and a delete pack button.

Hitting the install button brings up the error box again.

[Munaus]

post the log

logs can be found when clicking the Cog-Wheel button on the top right corner on the launcher window.
If you can't open the launcher the logs can also be found inside %appdata% -> Roaming -> .technic -> logs

Paste the content on pastebin.com or paste.ubuntu.com and give the link.

[drewajp]

Make sure you're using Java 8 and the launcher is set for stable version.