This has all the appearances of being "a Chilean package", you know, that kind of trap in which you are asked to deposit 10% of the prize for some type of deposit or for procedures, but then discover that they never had any intention of give yourself benefits and you don't have how to recover what you already paid.

I always remember the old phrase that said that if something seems too good to be true, it is most probable not true.

Although I have my doubts, when I consult, I see that in https://www.scamvoid.net/check/coinjer.com/ they do not classify it as scam, in another site (https://www.forexbrokerz.com/brokers/CoinJar -Review) make a list of the services and features of the site, but point out that it can be VERY slow and that causes problems, just in that sense I found a complaint from a client at https://www.reddit.com/r/BitcoinAUS/comments/7lcca1/cointreecom_australias_biggest_scam_website/ that was quite annoyed at the time for the delays to attend and the lack of effective response to the problem I had.