API call - sp_OAMethod - A certificate is required to complete client authentication - msxml3.dll

DECLARE @obj INT
DECLARE @sUrl NVARCHAR(200) = 'https:xxxxxxx.com/xxxx'

EXEC sp_OACreate 'MSXML2.ServerXMLHttp', @obj OUT
EXEC sp_OAMethod @obj, 'Open', NULL, 'POST', @sUrl, false
EXEC sp_OAMethod @obj, 'setRequestHeader', NULL, 'Content-Type', 'application/x-www-form-urlencoded'

EXEC sp_OAMethod @obj, 'send'


EXEC sp_OAGetProperty @obj, 'responseText'

EXEC sp_OAMethod @obj, 'send' statement in the above code returning the below error. Help us fix this, please.