Error while installing a package in uipath

I am getting the below error while installing the package UiPath.Slack.Activities.

I am tired of this error. Why does this error come ??

Hey @kkpatel,

Have a look at your settings in manage packages, do you have have all the tickboxes ticked?

I have just successfully installed the Slack package.

In my Default package list the Orchestrator package is not there. How can i get that ? In my other environment this package is there and also i am not getting any error while saving the Slack package.