https issue + freegeo deprecated API endpoint

My client is a paying subscriber, and I am tasked with fixing this plugin since it broke when he moved to a new host with HTTPS.

A few of the errors that console shows:

mixed content + the shutdown of the freegeoip

Mixed Content: The page at ‘https://www.oursite.com/nl-nl/over-oursite/verkooppunten/’ was loaded over HTTPS, but requested an insecure script ‘https://www.oursite.com/oursitewp2018/?simplemap-master-js=1&smpid=746&ver=4.9.8’. This request has been blocked; the content must be served over HTTPS.
jquery.min.js?ver=3.2.1:2 jQuery.Deferred exception: jQuery.getJSON(…).error is not a function TypeError: jQuery.getJSON(…).error is not a function
at HTMLDocument.<anonymous> (https://www.oursite.com/nl-nl/over-oursite/verkooppunten/:397:9)
at j (https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js?ver=3.2.1:2:29999)
at k (https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js?ver=3.2.1:2:30313) undefined
r.Deferred.exceptionHook @ jquery.min.js?ver=3.2.1:2
k @ jquery.min.js?ver=3.2.1:2
setTimeout (async)
(anonymous) @ jquery.min.js?ver=3.2.1:2
i @ jquery.min.js?ver=3.2.1:2
fireWith @ jquery.min.js?ver=3.2.1:2
fire @ jquery.min.js?ver=3.2.1:2
i @ jquery.min.js?ver=3.2.1:2
fireWith @ jquery.min.js?ver=3.2.1:2
ready @ jquery.min.js?ver=3.2.1:2
S @ jquery.min.js?ver=3.2.1:3
jquery.min.js?ver=3.2.1:2 Uncaught TypeError: jQuery.getJSON(…).error is not a function
at HTMLDocument.<anonymous> ((index):397)
at j (jquery.min.js?ver=3.2.1:2)
at k (jquery.min.js?ver=3.2.1:2)
(anonymous) @ (index):397
j @ jquery.min.js?ver=3.2.1:2
k @ jquery.min.js?ver=3.2.1:2
setTimeout (async)
r.readyException @ jquery.min.js?ver=3.2.1:2
(anonymous) @ jquery.min.js?ver=3.2.1:2
j @ jquery.min.js?ver=3.2.1:2
k @ jquery.min.js?ver=3.2.1:2
setTimeout (async)
(anonymous) @ jquery.min.js?ver=3.2.1:2
i @ jquery.min.js?ver=3.2.1:2
fireWith @ jquery.min.js?ver=3.2.1:2
fire @ jquery.min.js?ver=3.2.1:2
i @ jquery.min.js?ver=3.2.1:2
fireWith @ jquery.min.js?ver=3.2.1:2
k @ jquery.min.js?ver=3.2.1:2
setTimeout (async)
(anonymous) @ jquery.min.js?ver=3.2.1:2
i @ jquery.min.js?ver=3.2.1:2
fireWith @ jquery.min.js?ver=3.2.1:2
fire @ jquery.min.js?ver=3.2.1:2
i @ jquery.min.js?ver=3.2.1:2
fireWith @ jquery.min.js?ver=3.2.1:2
ready @ jquery.min.js?ver=3.2.1:2
S @ jquery.min.js?ver=3.2.1:3
(index):1 Mixed Content: The page at ‘https://www.oursite.com/nl-nl/over-oursite/verkooppunten/&#8217; was loaded over HTTPS, but requested an insecure script ‘https://freegeoip.net/shutdown&#8217;. This request has been blocked; the content must be served over HTTPS.