If you don't have an account PayPlug, thanks to register here : open a PayPlug account.
Once your account is live, please go to : https://www.payplug.fr/portal/ecommerce/autoconfig
Enter your PayPlug login and password, you should get a text that look similar to that one :
{"status":"200","yourPrivateKey":"-----BEGIN RSA PRIVATE KEY-----
\nMIIEezaezaAKCAQEAoLIv2Jr6GYjQQwX2tKVYAmihWwYwihBVIl7L6YGyssZxuvQC\n7IMuddWQ
bNqKqBFHFyg\/jzKGyP2VCu6oJKmWsObUQR6ymNpFWoQa07P3QiSocDp1\nk1PCmGnodk4VeCj
lhDobWHPKUuYIObzwuzU2cWRwhXADL1aZHM48dlNHU3CkuiBk\n538r\/BlrAgXYGQ8seG6nHihI
xbWVsz3SgqgoDapwqJ2lKq86scEQ0vClIalsHLs0Q8okFv+2\/5J\nQ2ZrAoGAEBwMWwVO\/IgHaw
frw7WyOexgijiFSa6\/t+\/ToZfo+KpAggvv2WoBWbm\/\nWjIGnmTj6hxPSEIyKs62UrAfKUMVOTTg
uGcik0MMEJ16e6IY540\/0PiR0Wbexdtj\nPq36H7wzDTmsO8xFCbaVgoSqtGb6tbtTDg1midB6s9T
GLpq1tEM=\n-----END RSA PRIVATE KEY--
---","url":"https:\/\/www.payplug.com\/p\/LZKh","payplugPublicKey":"-----BEGIN PUBLIC KEY-
----\
nMIIBdqsdqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAtN4dpK368PEEYKeee7S5\n1m2a8GUFLDA
Z\/HgRI1H6diYt87gzDPftn1UyW96YuIBed0T0dtl0tuABaIgGeddR\nuo3zfMpkyYWMezaEMKzEY5W
IyaaWoVYJaZU5DWzCiroKcnUJgKm41RL32\/CHU\nSFoymxjOOzpvkazbaY+Ql2GYev2QwKAf7ldq
s3frjQYXEFIwYnt6ZET8wPUwX\nMdF0hRaZYlaDQrCB2S\/+k4Djb8mXqVkJ0qqgItycL05zyysJw\/I
GMr2zZ5hQSnfN\nCJ+i33ywnoT\/qctGgLW4bGuGdTdcbA7VzdxhXtHaAQjuJvrf+twNCQSLCMbZ6
B\n-----END PUBLIC KEY-----\n","amount_min":1,"amount_max":5000,"currencies":["EUR"]}
Copy the full text (from { to }), and got to the page:
http://app.crownmakers.com/en/admin/preferences#tab_payment
In the left menu, please select Payplug, then fill the right form:
* with your PayPlug login
* with your Payplug password
* paste the previous text starting with { and ending by }.
Click on OK, that's it, you're ready.
