You do not need the profileKeys section. You only need the contents inside ["profiles"] . Copy everything from the opening after ["BestUIever"] = to the closing before the next bracket.
local conversionFunctions = -- ... ["13.00"] = function() self:ConvertFrom1300(profileName) end, elvui profile converter
ElvUI has undergone numerous structural changes over the years. A profile string (the long block of text used to share settings) exported from a modern Retail version will not work on older versions like the ElvUI Backport (3.3.5) . Users often encounter an "Error decoding data" You do not need the profileKeys section