Easier/simpler way of importing an SSIS package -- help needed!

Folks,
Looking for advice on the best way to import a package. I inherited a system (Sql Server 2019) with an existing SSIS package. The installation notes indicate that you have to be on the server using SSMS v18. The installation notes indicate:

  1. To be on the server using SSMS v18 only (apparently does not work with any other version!)
  2. Copy across the .dtsx file and use the "Import Package" for SSIS (under the MSDB folder) to import the package (SSIS v15.0.2)

I have done this and it works, however security is giving us warning messages as this is an old SSMS version. So, basically we cannto continue using this technique.
I tried therefore connecting Integration Services server from SSMS v19 from my own PC but I get the following eror message:

Connecting to the Integration Services service on the computer "yyy" failed with the following error: "Access is denied."

Just wondering is there anyway around this? My account is sysadmin on the box. Is there anything I can do to enable this?

Also, wider than this, what is the best way to deploy SSIS packages in general? Any advice/guidence/easier techniques much appreciated...
J.