Avoid Inkahousing.nl
Inkahousing.nl (or any other website they pop up once they have been found out) is effectively a scam organisation. Do not deal with them.
They seem polite and nice at the beginning but once they have your property under management, they show their true colours, for example: not paying the rent or paying less than agreed, letting the tenants damage the property, not letting the property owner see the property and what is happening to it, or break contract in a number of different ways too long to all list here.
Hiding behind Dutch tenant laws (which are very strict), they are able to hold these properties for years until you are forced to go through expensive legal actions to remove them and then it is still very difficult even when they are repeatedly breaking contract because the law supports tenants even when they are causing many problems.
So, once they are in they are almost impossible to get out and can act as badly as they choose, knowing there are few measures to remove them.