Hello I am new to Salesforce integration, 

I need a way to Store the value i get by making the API callout to custom field 

is there a workaround for this?

Create Formula and Roll-Up Summary Fields

From Setup, click Object Manager, and select Job Application.
Click Fields & Relationships, then click New.
For Data Type, choose Roll-Up Summary, and click Next.
For Field Label, enter Number of Reviews.
Click Next.
Select Reviews from the Summarized Object picklist.
Select Count as the Roll-Up Type.
Select All records should be included in the calculation as the Filter Criteria.
Click Next, Next, then Save & New.

 

have create it according to this but still getting an error

Create Formula and Roll-Up Summary Fields

From Setup, click Object Manager, and select Job Application.
Click Fields & Relationships, then click New.
For Data Type, choose Roll-Up Summary, and click Next.
For Field Label, enter Number of Reviews.
Click Next.
Select Reviews from the Summarized Object picklist.
Select Count as the Roll-Up Type.
Select All records should be included in the calculation as the Filter Criteria.
Click Next, Next, then Save & New.

 

have create it according to this but still getting an error

I have created a Quick Action button on Itemsetup Object and calling a Lightning component when clickon Button.

When Click on Action button , Popup is showing when I logged in as System Admin. But when I logged in as other user I can't see popup. I have not specfied any permission to visbility of lightning popup. But it is not showing, Why? 

Can anyone help me on this?

Thanks in Advance !